1. Field of the Invention
This invention relates to a method for isolating resolved amino acids.
2. Description of the Prior Art
In the prior art, the isolation of resolved amino acids is achieved by first hydrolyzing a racemic mixture having the formula EQU (DL)--H.sub.2 N--CHX--COOY,
with an esterase to yield a solution comprising (L)--H.sub.2 N--CHX--COOH and (D)--H.sub.2 N--CHX--COOY.
In order to isolate (L)--H.sub.2 N--CHX--COOH from this solution, several recrystallations from water are required in the prior art. This recrystallation method is very laborious since (L)--H.sub.2 N--CHX--COOH and (D)--H.sub.2 N--CHX--COOY have almost the same solubilities in water. Therefore, utilizing tedious prior art recrystallization methods even highly skilled technicians can expect only marginal separation of the resolved amino acid moieties and low yields of (L)--H.sub.2 N--CH--COOH.
In addition, when the resolved amino acid (L)--H.sub.2 N--CHX--COOH is employed in a peptide synthesis, other than as the first C-terminal amino acid in a solution technique, one must always protect the N-terminus of the resolved amino acid with a suitable N-terminus protecting group. This step further reduces the amount of product obtained via the prior art process.